Stone Brewing, whose bold ales and irreverent tone have helped reinvent American beer, now plans to do the same thing in the brewing industry’s historic heartland, Germany.

On Saturday, the Escondido-based company unveiled plans for a $25 million plant in Berlin.

When the new operation opens, probably in late 2015, it will be able to make 85,000 barrels of beer annually and distribute across Europe. It will also challenge entrenched notions about what beer ought to be in the nation that did so much to define the beverage.

“We have no attitude that we are coming to save anybody or conquer anybody,” Koch said, acknowledging Germany’s “nascent” craft brewing movement is already challenging that country’s brewing giants.

“We are coming to add our shoulder, to help push that boulder up the hill.”

This hill is steep, though, and for an American brewery to scale these heights represents a reversal of centuries-old roles. Beer may not have been born in Germany — the beverage’s roots can be traced to ancient Sumeria — but German brewers have a deep, storied tradition. Weihenstephan, founded in 1040, is the world’s oldest operating brewery; its training academy is considered the Harvard of the brewing sciences. Drinkers around the globe quaff German beer styles, from golden lager to hefeweizen, while the rigorous Teutonic brewing techniques are the international industry standards.

German immigrants founded many of the largest American beer companies, from Pabst to Anheuser-Busch. By the mid-20th century, though, Old Country brewers scorned those mass-produced New World lagers, arguing that America’s thin, watery brews were no match for their hearty German counterparts.

By the 1980s, though, new American breweries were reviving traditional techniques and styles. Stone, which Koch and Steve Wagner founded in 1996, produced aromatic, bitter, hop-forward pale ales and India pale ales, as well as strong brews with pugnacious names such as “Arrogant Bastard Ale.”

Like other upstart breweries across the country — Delaware’s Dogfish Head, say, or Northern California’s Sierra Nevada — Stone won a passionate following and rapid growth. Now the 10th largest craft brewery in the U.S., Stone operates tasting rooms, an organic farm and two of San Diego County’s largest restaurants. Last year it produced more than 213,000 barrels of beer and reported net revenue of $137 million. Even as the Berlin venture takes shape, Stone is studying proposals to open another brewery on the East Coast.

“Stone Brewing has turned the conception of beer upside down in the U.S.,” said Sylvia Kopp, head of the Berlin Beer Academy, a company that conducts seminars, hosts beer tastings and organizes tours.

How will Stone’s in-your-face style play in Germany?

“This might irritate some and turn others off,” Kopp said. “Some will get attracted, hopefully more will learn about craft beer. It will be interesting to see how Stone will present themselves and who they will connect with in Germany and Europe.”